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Hyeokjun Kang,Jeong-Hwan Oh,Daeun Choi,Hidemasa Takana,Sooseok Choi 한국진공학회(ASCT) 2021 Applied Science and Convergence Technology Vol.30 No.6
Presently, the use of bituminous coals as a heating source in the cement industry has led to an increase in carbon dioxide emissions. In this study, the thermal flow characteristics inside a waste combustion chamber constituting multiple thermal plasma jets was numerically analyzed. The waste combustion process was applied as a heating source to produce the raw materials of cement. The design and operation of the waste combustion process were optimized through numerical analysis using the magnetohydrodynamics and computational fluid dynamics code. The thermal flow characteristics inside the waste combustion chamber were numerically analyzed in accordance with adjusting the chamber width, injection angle of the torch, and combustion air temperature. As a result, the temperature in the range of 1,600–2,200 K was widely distributed at the center of the chamber. The optimized conditions are as follows: 400 mm chamber width, 20° injection angle, and 1,000 K combustion air temperature. The waste combustion chamber constituting multiple thermal plasma jets was constructed based on the numerical results. It was concluded that plasma jets generate a sufficient temperature to treat waste plastics.
Typologies of Serial Arson: Explorative Study based on Latent Class Analysis
Hyeokjun Kwon,Jonghan Sea 한국자료분석학회 2020 Journal of the Korean Data Analysis Society Vol.22 No.6
Serial arson is a severe crime than other violent crimes in severity of damage. Nonetheless, there is rarely been studied in terms of motivation and crime scene behaviors. This study empirically aims to investigate typology of serial arson based on motives and crime scene actions for helping to solve arsons. By Latent Class Analysis (LCA), a sample of 39 serial arsonists from the Korean National Data-base (i.e., SCAS) was analyzed. A cross-tabulation analysis was conducted to see relationships between offenders’ motive and crime scene information. In addition, chi-square analyses were used in between arson types and sociodemographic characteristics. As a result, types of serial arsons were classified into three classes, respectively; hybrid, revenge, release on motives and distant-inside, distant-outside, nearby-inside on crime scene behaviors. The associations by these classes possibly provide importation source to hypothesize arsons’ motive from crime scene actions for efficient policing. This empirical study could put stepstone on the offenders’ profiling to prioritize suspect especially in fire investigation.